为了提高遍历矩阵的随机性和安全性,实现对图像信息的有效保护,提出了遍历矩阵构造的新方法,并结合像素值扩散设计了一种有效的图像加密算法.首先,利用混沌序列构造出完全不依赖载体图像灰度值的整数遍历矩阵,并利用此矩阵在图像空域进行迭代置乱,改进了传统遍历仅按特定路线扫描的局限性,以及对遍历周期和次数的过分依赖性；接着采用一个均匀分布的新混沌数列实现像素值扩散,改变了图像的统计特性,并使混沌映射不可逆；最后,构造出符合密码使用习惯的密钥生成系统,形成相对完整的加密体系,实现了图像加密.从统计特性、密钥空间、像素相关性、密钥敏感性、差分分析等多方面对算法的安全性进行了分析,结果表明,算法密钥空间大,抗攻击能力强,安全性高,实用性强.%In order to improve the randomness and safety of the ergodic matrix and effective protect image information, a new image encryption method was proposed based on the ergodic matrix and pixel value diffusion. First, the input image was permuted independently by using the ergodic matrixes which were generated by discrete chaotic system. And then pixel value diffusion was realized by a uniformly distributed chaotic sequence. The statistical properties of the image got changed and the chaotic mapping was made irreversible; Finally, password generation mechanism was constructed to not only comply with usage of cryptography, but also to enhance usability. A relatively complete encryption system was built up to achieve the image encryption. The security had been analyzed using statistical analysis, key sensitivity analysis, differential analysis, key space analysis, etc. The results demonstrate that the algorithm ha3 good properties of confusion, diffusion and statistic distribution of pixel value, so the algorithm has better scrambling effect in comparison with other approaches. It is safe and practical and easy to realize.
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